PERF: Add type-hints in tzconversion.pyx (#55241)

Author: rhshadrach

doc/source/whatsnew/v2.2.0.rst

@@ -238,7 +238,7 @@ Performance improvements
 - Performance improvement in :meth:`DataFrame.sort_index` and :meth:`Series.sort_index` when indexed by a :class:`MultiIndex` (:issue:`54835`)
 - Performance improvement in :meth:`Index.difference` (:issue:`55108`)
 - Performance improvement when indexing with more than 4 keys (:issue:`54550`)
--
+- Performance improvement when localizing time to UTC (:issue:`55241`)
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_220.bug_fixes:

pandas/_libs/tslibs/tzconversion.pyx

@@ -462,7 +462,7 @@ cdef str _render_tstamp(int64_t val, NPY_DATETIMEUNIT creso):
 
 
 cdef _get_utc_bounds(
-    ndarray vals,
+    ndarray[int64_t] vals,
     int64_t* tdata,
     Py_ssize_t ntrans,
     const int64_t[::1] deltas,
@@ -472,7 +472,7 @@ cdef _get_utc_bounds(
     # result_a) or right of the DST transition (store in result_b)
 
     cdef:
-        ndarray result_a, result_b
+        ndarray[int64_t] result_a, result_b
         Py_ssize_t i, n = vals.size
         int64_t val, v_left, v_right
         Py_ssize_t isl, isr, pos_left, pos_right